GS/HW: Add debug blend setting.

Will enable SW blend and disable many optimizations.

pcsx2-qt/Settings/GraphicsAdvancedSettingsTab.ui

@@ -321,6 +321,13 @@
           </property>
          </widget>
         </item>
+        <item row="2" column="0">
+         <widget class="QCheckBox" name="useDebugBlend">
+          <property name="text">
+           <string>Use Debug Blend</string>
+          </property>
+         </widget>
+        </item>
        </layout>
       </item>
      </layout>
@@ -355,6 +362,7 @@
   <tabstop>palFrameRate</tabstop>
   <tabstop>overrideTextureBarriers</tabstop>
   <tabstop>useDebugDevice</tabstop>
+  <tabstop>useDebugBlend</tabstop>
   <tabstop>disableFramebufferFetch</tabstop>
   <tabstop>disableShaderCache</tabstop>
   <tabstop>disableVertexShaderExpand</tabstop>

pcsx2-qt/Settings/GraphicsSettingsWidget.cpp

@@ -225,6 +225,7 @@ GraphicsSettingsWidget::GraphicsSettingsWidget(SettingsWindow* settings_dialog,
 	//////////////////////////////////////////////////////////////////////////
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.useBlitSwapChain, "EmuCore/GS", "UseBlitSwapChain", false);
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.useDebugDevice, "EmuCore/GS", "UseDebugDevice", false);
+	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.useDebugBlend, "EmuCore/GS", "UseDebugBlend", false);
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.disableMailboxPresentation, "EmuCore/GS", "DisableMailboxPresentation", false);
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.extendedUpscales, "EmuCore/GS", "ExtendedUpscalingMultipliers", false);
 	SettingWidgetBinder::BindWidgetToIntSetting(sif, m_advanced.exclusiveFullscreenControl, "EmuCore/GS", "ExclusiveFullscreenControl", -1, -1);
@@ -766,6 +767,9 @@ GraphicsSettingsWidget::GraphicsSettingsWidget(SettingsWindow* settings_dialog,
 		dialog()->registerWidgetHelp(m_advanced.useDebugDevice, tr("Enable Debug Device"), tr("Unchecked"),
 			tr("Enables API-level validation of graphics commands."));
 
+		dialog()->registerWidgetHelp(m_advanced.useDebugBlend, tr("Enable Debug Blend"), tr("Unchecked"),
+			tr("Forces SW blending and disables several optimizations."));
+
 		dialog()->registerWidgetHelp(m_advanced.gsDownloadMode, tr("GS Download Mode"), tr("Accurate"),
 			tr("Skips synchronizing with the GS thread and host GPU for GS downloads. "
 			   "Can result in a large speed boost on slower systems, at the cost of many broken graphical effects. "

pcsx2/Config.h

@@ -760,6 +760,7 @@ struct Pcsx2Config
 					PCRTCOverscan : 1,
 					IntegerScaling : 1,
 					UseDebugDevice : 1,
+					UseDebugBlend : 1,
 					UseBlitSwapChain : 1,
 					DisableShaderCache : 1,
 					DisableFramebufferFetch : 1,
@@ -791,7 +792,7 @@ struct Pcsx2Config
 					PreloadFrameWithGSData : 1,
 					Mipmap : 1,
 					HWMipmap : 1,
-					HWAccurateAlphaTest: 1,
+					HWAccurateAlphaTest : 1,
 					HWAA1 : 1,
 					ManualUserHacks : 1,
 					UserHacks_AlignSpriteX : 1,

pcsx2/GS/GSState.cpp

@@ -4642,13 +4642,13 @@ GSState::PRIM_OVERLAP GSState::GetPrimitiveOverlapDrawlistImpl(bool save_drawlis
 			};
 
 			// First check: see if the triangles are part of a triangle strip.
-			if (!got_bbox && !using_aa1)
+			if (!got_bbox && !using_aa1 && !GSConfig.UseDebugBlend)
 			{
 				got_bbox = CheckTriangleStrips(j, skip, bbox, saved_tristrip);
 			}
 
 			// Second check: see if the triangles are part of triangle fan.
-			if (!got_bbox && !using_aa1)
+			if (!got_bbox && !using_aa1 && !GSConfig.UseDebugBlend)
 			{
 				got_bbox = CheckTriangleQuads.template operator()<1>(j, skip, bbox);
 			}

pcsx2/GS/Renderers/HW/GSRendererHW.cpp

@@ -6955,27 +6955,26 @@ void GSRendererHW::EmulateBlending(int rt_alpha_min, int rt_alpha_max, DATEOptio
 			break;
 	}
 
-	if (features.framebuffer_fetch)
-	{
+	const bool force_sw_blending =
 		// If we have fbfetch, use software blending when we need the fb value for anything else.
 		// This saves outputting the second color when it's not needed.
-		if (one_barrier || m_conf.require_full_barrier)
-		{
-			sw_blending = true;
-			color_dest_blend = false;
-			accumulation_blend = false;
-			blend_mix = false;
-		}
-	}
+		(features.framebuffer_fetch && (one_barrier || m_conf.require_full_barrier)) ||
 
-	if (m_conf.ps.IsFeedbackLoopDepth() && !features.depth_feedback)
-	{
 		// If we are doing depth feedback with a second RT we must use SW blending to avoid
 		// mixing dual source blending with multiple render targets.
+		(m_conf.ps.IsFeedbackLoopDepth() && !features.depth_feedback) ||
+		
+		// Force SW blending with barriers.
+		GSConfig.UseDebugBlend;
+	
+	if (force_sw_blending)
+	{
 		sw_blending = true;
 		color_dest_blend = false;
 		accumulation_blend = false;
 		blend_mix = false;
+		color_dest_blend2 = false;
+		blend_zero_to_one_range = false;
 	}
 
 	// Color clip

pcsx2/ImGui/FullscreenUI_Settings.cpp

@@ -4979,6 +4979,8 @@ void FullscreenUI::DrawAdvancedSettingsPage()
 		MenuHeading(FSUI_CSTR("Graphics"));
 		DrawToggleSetting(bsi, FSUI_ICONSTR(ICON_FA_BUG, "Use Debug Device"), FSUI_CSTR("Enables API-level validation of graphics commands."), "EmuCore/GS",
 			"UseDebugDevice", false);
+
+		DrawToggleSetting(bsi, FSUI_ICONSTR(ICON_FA_BUG, "Use Debug Blend"), FSUI_CSTR("Forces SW blending and disables several optimizations."), "EmuCore/GS", "UseDebugBlend", false);
 	}
 
 	EndMenuButtons();

pcsx2/Pcsx2Config.cpp

@@ -754,6 +754,7 @@ Pcsx2Config::GSOptions::GSOptions()
 	HWMipmap = true;
 	HWAccurateAlphaTest = false;
 	HWAA1 = false;
+	UseDebugBlend = false;
 
 	ManualUserHacks = false;
 	UserHacks_AlignSpriteX = false;
@@ -1041,6 +1042,7 @@ void Pcsx2Config::GSOptions::LoadSave(SettingsWrapper& wrap)
 	SettingsWrapBitBoolEx(HWMipmap, "hw_mipmap");
 	SettingsWrapBitBool(HWAccurateAlphaTest);
 	SettingsWrapBitBool(HWAA1);
+	SettingsWrapBitBool(UseDebugBlend);
 	SettingsWrapIntEnumEx(AccurateBlendingUnit, "accurate_blending_unit");
 	SettingsWrapIntEnumEx(TextureFiltering, "filter");
 	SettingsWrapIntEnumEx(TexturePreloading, "texture_preloading");